<p>A distributed, real-time database could be used to implement a shared whiteboard architecture used for communication between mobile nodes, in an ad-hoc network. This kind of application implies specific requirements on how the database handles replication and consistency between replicas (global consistency). Since mobile nodes are likely to disconnect from the network and connect again at unpredictable times, and since a node may be disconnected an arbitrary amount of time, this needs to be treated as normal operation, and not as failures.</p><p>The replication scheme used in the DeeDS architecture, and the PRiDe replication protocol are both suitable for a shared whiteboard architecture as described above. Since the mobile nodes are likely to be some kind of hand-held device (e.g., used by rescue personnel to exchange information), the database system should be suitable for use in embedded systems. The Polyhedra Real-Time Relational Database (RTRDB) and the TimesTen database are two such systems. A problem is that neither of these two database systems have a replication scheme suitable for use in the previously described type of architecture.</p><p>This dissertation presents two design proposals for how to extend the Polyhedra RTRDB with support for multi-master replication of data using full replication and eventual consistency. One design proposal is based on the DeeDS architecture and the other is based on the PRiDe replication protocol. The proposal based on DeeDS puts a number of requirements on the underlying database and is not easy to port to another DBMS since it makes use of Polyhedra specific API’s. The proposal based on PRiDe on the other hand requires no instrumentation of the underlying database and is thus easier to port to other database systems.</p>

<p>Recovery is a fundamental service in database systems. In this work, we present a new mechanism for diskless real-time recovery in fully replicated distributed real-time database systems. Traditionally, recovery has relied on disk-resident redundant data. Unfortunately, disks cannot always be used in real-time systems since these systems are sometimes used in environments which do not allow the use of disks. Also, minimizing the amount of hardware can save money, especially in mass-produced products. Instead of loading the database from disk, our recovery mechanism enables a restarted node to retrieve a copy of the database from an arbitrary remote node. The recovery mechanism does not violate timeliness during normal processing and, during recovery, all nodes except for the recovering node can guarantee the timeliness of critical transactions. The mechanism uses fuzzy checkpointing to copy the database to the recovering node. Fuzzy checkpointing has been chosen since it copies the database without regard to concurrency control and, thus, does not increase data contention in the database. We conclude that the suggested recovery mechanism is a feasible option for fully replicated distributed real-time database systems.</p>

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-07-18T12:16:27Z No. of bitstreams: 1 arquivot total.pdf: 1749338 bytes, checksum: 27366dd411e0d722fa03c5cd9e087c4e (MD5) / Made available in DSpace on 2016-07-18T12:16:27Z (GMT). No. of bitstreams: 1 arquivot total.pdf: 1749338 bytes, checksum: 27366dd411e0d722fa03c5cd9e087c4e (MD5) Previous issue date: 2015-04-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work presents the results of research conducted in the city of Sapé, PB, that had as objective identify the perception that the users of the social assistance politics have about the eventual benefits, considering the perspectives of the right and of the help, and analyzing it as its repercussions for the process of affirming the social assistance as a right. Thus, the data collecting was conducted between the months of November 2013 and December 2014 and was made through the observation, by the review of the documents and literature pertinent and by the application of the formularies with the users that had access the benefits, with reference to the month of August 2013. Altogether, it was identified that the perception of beneficiaries reflects the limitations presents in the legal and operational plans, approaching more of the help than the notion of the right, setting is, therefore, an obstacle to the consolidation of the right to social assistance. Starts by the presupposition that the social assistance, instituted as right ensured by the Constitution and by specific law, don't have the faculty of, by itself, leave the traces of one past full of practices and conceptions misrepresented. For this, it is necessary to stimulate political projections that guides their management to the sense of break this paradigm, at one movement that integrate all their provisions to the assurance of the users' rights. The regulation and operation of the eventual benefits, as components of the Brazilian’s System of Social Assistance (SUAS), presents itself as an indispensable element in this process of consolidation, once these have particular association with welfarism and clientelism expresses along the career of the social assistance and that, and how is possible to deduce from the data that describes the reality of the manage this right, presented in this discussion, still resist insistently. / Este trabalho apresenta os resultados da pesquisa realizada no município de Sapé, PB, que teve por objetivo identificar a percepção que os usuários da política de assistência social detêm sobre os benefícios eventuais, considerando as perspectivas do direito e da ajuda, e analisando-a quanto aos seus rebatimentos para o processo de afirmação da assistência social enquanto direito. Para tanto, a coleta de dados foi realizada entre os meses de novembro de 2013 e dezembro de 2014 e se deu através da observação, do levantamento documental e bibliográfico pertinente e da aplicação de formulários junto aos usuários que acessaram os benefícios eventuais, tendo por referência o mês de agosto de 2013. De modo geral, identificou-se que a percepção dos beneficiários é reflexo das limitações presentes no plano legal e operativo, aproximando-se mais da noção de ajuda do que da do direito, configurando-se, portanto, em um obstáculo para a consolidação do direito à assistência social. Essa constatação fundamenta-se no pressuposto de que a assistência social, ao se constituir como direito assegurado pela Constituição Federal e por Lei específica, não detém a faculdade de, por si só, abandonar os vestígios de um passado abarrotado de práticas e concepções deturpadas. Para tanto, é preciso estimular projeções políticas que orientem sua gestão no sentido da quebra deste paradigma, num movimento que integralize todas as suas provisões para a garantia do direito dos usuários desta política. A regulamentação e operacionalização dos benefícios eventuais, enquanto componentes do Sistema Único de Assistência Social (SUAS) brasileiro, se apresenta como elemento indispensável nesse processo de consolidação, uma vez que estes possuem particular associação ao assistencialismo e ao clientelismo expressos por muito tempo na trajetória da assistência social.

Recovery is a fundamental service in database systems. In this work, we present a new mechanism for diskless real-time recovery in fully replicated distributed real-time database systems. Traditionally, recovery has relied on disk-resident redundant data. Unfortunately, disks cannot always be used in real-time systems since these systems are sometimes used in environments which do not allow the use of disks. Also, minimizing the amount of hardware can save money, especially in mass-produced products. Instead of loading the database from disk, our recovery mechanism enables a restarted node to retrieve a copy of the database from an arbitrary remote node. The recovery mechanism does not violate timeliness during normal processing and, during recovery, all nodes except for the recovering node can guarantee the timeliness of critical transactions. The mechanism uses fuzzy checkpointing to copy the database to the recovering node. Fuzzy checkpointing has been chosen since it copies the database without regard to concurrency control and, thus, does not increase data contention in the database. We conclude that the suggested recovery mechanism is a feasible option for fully replicated distributed real-time database systems.

The effect of using the eventual consistency model is evaluated, compared to the effect of immediate consistency, by increasing the stabilization time in both models and using the immediate consistent system as a baseline for evaluations. The immediate consistent system performs better if the information and the decisions are replicated adequately fast throughout the system. When the stabilization time increases the effectiveness of eventual consistency emerges, which is most obvious when time constraints make it difficult to propagate information and decisions. By using a simulation to extract data for evaluations, it is verified in this research that as the stabilization time between different parts of a system increases, the eventual consistency will always outperform the immediate consistent system. This statement is valid in all situations where consistency models are useful. Of secondary importance in the research, by adding more decision layers to the eventual consistency model, the performance output is increased significantly, as swift and less well calculated decisions can be thwarted and corrected using the second decision layer.

A distributed, real-time database could be used to implement a shared whiteboard architecture used for communication between mobile nodes, in an ad-hoc network. This kind of application implies specific requirements on how the database handles replication and consistency between replicas (global consistency). Since mobile nodes are likely to disconnect from the network and connect again at unpredictable times, and since a node may be disconnected an arbitrary amount of time, this needs to be treated as normal operation, and not as failures. The replication scheme used in the DeeDS architecture, and the PRiDe replication protocol are both suitable for a shared whiteboard architecture as described above. Since the mobile nodes are likely to be some kind of hand-held device (e.g., used by rescue personnel to exchange information), the database system should be suitable for use in embedded systems. The Polyhedra Real-Time Relational Database (RTRDB) and the TimesTen database are two such systems. A problem is that neither of these two database systems have a replication scheme suitable for use in the previously described type of architecture. This dissertation presents two design proposals for how to extend the Polyhedra RTRDB with support for multi-master replication of data using full replication and eventual consistency. One design proposal is based on the DeeDS architecture and the other is based on the PRiDe replication protocol. The proposal based on DeeDS puts a number of requirements on the underlying database and is not easy to port to another DBMS since it makes use of Polyhedra specific API’s. The proposal based on PRiDe on the other hand requires no instrumentation of the underlying database and is thus easier to port to other database systems.

Replication primarily provides data availability by having multiple copies over different systems and is exploited to make distributed systems scalable in num- bers and geographical areas. Placing a replica closer to the source of request can also significantly reduce the time required to service the request, improv- ing applications’ performance. However, modifications done at a single copy need to be propagated to all the standing copies to maintain the data’s consis- tency. Over the years, numerous strategies have been proposed for handling the tradeoff between consistency and availability, of which the majority pro- vides either strong consistency or eventual consistency. These models do not provide sufficient compatibility for developing modern applications for geo- distributed (edge) environments.Conflict-Free Replicated Data Types (CRDT) provides a new model of consistency referred to as strong eventual consistency. In principle, CRDTs guarantee conflict-free merge even when the updates arrive out of order using simple mathematical properties. Lasp is a coordination free distributed pro- gramming model for building modern distributed applications using CRDTs. Lasp uses a gossip protocol for disseminating state changes to all replicas in the system. The current implementation of gossip in Lasp is agnostic to the application’s behavior in propagating the updates efficiently to critical repli- cas in the system. In the thesis, we introduce an application-specific feature to optimize the dissemination of updates in Lasp. The proposed algorithm propagates the updates by catering to the different consistency requirements of the replicas in the system. The experimental results on a topology of 100 replicas found that the update latency at critical replicas with high consistency requirements is reduced by 40–50%, and the total bandwidth consumption in the system is reduced by 4–8% without significant repercussion on other repli- cas in the system. / Datareplikering erbjuder primärt tillgänglighet genom att tillhandahålla mul- tipla kopior fördelat över olika system, och utnyttjas för att göra distribuerade system skalbara i antal och över geografiska områden. Att placera en replika nära källan till en förfrågan kan dessutom signifikant reducera tiden det krävs att besvara förfrågan vilket förbättrar applikationens prestanda. Modifikatio- ner gjorda på en av kopiorna måste dock propageras till alla stående kopior för att upprätthålla datans konsistens . Över tid har många strategier föreslagits för att hantera avvägningen mellan konsistens och tillgänglighet, där majorite- ten erbjuder antingen stark eller eventuell konsistens. Dessa modeller erbjuder inte tillräcklig kompatibilitet för utveckling av moderna applikationer för geo- distribuerade (edge) miljöer.Konfliktfria replikerade datatyper (CRDT) erbjuder en ny modell av konsi- stens som kallas stark eventuell konsistens. I princip garanterar CRDTer kon- fliktfria sammanslagningar trots att uppdateringar sker i oordning, genom att använda dess matematiska egenskaper. Lasp är en koordineringsfri distribue- rad programmeringsmodell för att bygga moderna distribuerade applikationer med hjälp av CRDTer. Lasp använder skvallerprotokoll för att sprida tillstånds- förändringar till alla replikor i systemet. Den nuvarande implementationen av skvaller i Lasp är agnostiskt för applikationens beteende relaterat till effektiv propagering av uppdateringar till kritiska replikor i systemet. I det här exa- mensarbetet introducerar vi applikationsspecifik funktionalitet för att optime- ra spridandet av uppdateringar i Lasp. Den föreslagna algoritmen sprider upp- dateringarna genom att tillgodose de olika konsistenskraven för replikorna i systemet. Experimentella resultat i en topologi av 100 replikor visade att upp- dateringslatensen vid kritiska replikor med höga konsistenskrav minskas med 40–50% och att den totala bandbreddskonsumtionen i systemet minskas med 4–8% utan signifikanta negativa följder för andra replikor i systemet.

Este trabajo presenta un catálogo de técnicas y patrones de diseño aplicados actualmente en bases de datos NoSQL. El enfoque propuesto consiste en una presentación del estado del arte de las bases de datos NoSQL, una exposición de los conceptos claves relacionados y una posterior exhibición de un conjunto de técnicas y patrones de diseño orientados a la escalabilidad y alta disponibilidad. Para tal fin, • Se describen brevemente las características principales de los bases de datos NoSQL, cuales son los factores que motivaron su aparición, sus diferencias con sus pares relacionales, se presenta el teorema CAP y se contrasta las propiedades ACID contra las BASE. • Se introducen las problemáticas que motivan las técnicas y patrones de diseño a describir. • Se presentan técnicas y patrones de diseños que solucionen las problemáticas. • Finalmente, se concluye con un análisis integrador, y se indican otros temas de investigación pertinentes.

Made available in DSpace on 2016-04-27T16:32:22Z (GMT). No. of bitstreams: 1 Lorena Rodrigues de Oliveira.pdf: 651971 bytes, checksum: 7e24670a3ef09c0c10a8353d95d619a3 (MD5) Previous issue date: 2010-08-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The temporary teachers working in schools in state of Sao Paulo as a means of remedying the problem of shortages of professors, replacing any absences. There are about 17,000 teachers working as a eventual teacher, which can be considered on duty at school, without any guarantee and employment stability. The main objective of this research is to draw a profile of teachers in any Board of Education Caieiras, metropolitan region of São Paulo state and identify the vision they express about their work and their situation professional. It's knowing who they are, as perceive their work and their relationship with the organization school. For this, a search was conducted qualitative, whose instruments for collecting data, in 2009, were the questionnaires, semi-structured interviews with teachers and any document analysis. The research has as reference, mainly the work of Gimeno Sacristán (1999), Vorraber (1995) and Huberman (1995). Results presented in charts and tables suggest that interviewed teachers are mostly young teachers with little training time, are formed predominantly in private institutions. In relation to the vision that express about their work demonstrate that they feel devalued and exhibit a difficult relationship with other teachers in schools and working with students / Os professores eventuais atuam nas escolas da rede estadual de São Paulo como meio de sanar o problema das faltas dos professores titulares, substituindo eventuais ausências. São cerca de 17 mil professores trabalhando como professores eventuais, que podem ser considerados plantonistas da escola, sem qualquer garantia e estabilidade profissional. O objetivo principal desta pesquisa é traçar um perfil de professores eventuais na Diretoria de Ensino de Caieiras, região metropolitana do estado de São Paulo e identificar a visão que eles expressam acerca do seu trabalho e de sua situação profissional. Trata-se de conhecer quem são, como percebem o seu trabalho e sua relação com a organização escolar. Para tanto, foi realizada uma pesquisa qualitativa, cujos instrumentos para a coleta de dados, no ano de 2009, foram a aplicação de questionários, entrevistas semi-estruturadas com professores eventuais e análise documental. A pesquisa tem como referencial, principalmente, os trabalhos de Gimeno Sacristán (1999), Vorraber (1995) e Huberman (1995). Os resultados apresentados em quadros e tabelas sugerem que os professores entrevistados são, na maior parte, professores jovens e com pouco tempo de formação; são formados, predominantemente, em instituições privadas. Em relação à visão que expressam acerca de seu trabalho demonstram que se sentem desvalorizados e manifestam uma difícil relação com os demais professores das escolas em que atuam e com os alunos

Made available in DSpace on 2016-04-28T18:22:10Z (GMT). No. of bitstreams: 1 Cacilda Aparecida da Silva.pdf: 586246 bytes, checksum: fa79d8b0b9f2d7bc0e906b38b09ddd67 (MD5) Previous issue date: 2010-10-15 / Secretaria da Educação do Estado de São Paulo / This research aims at understanding critically the construction process of meanings shared by a group of teachers from a public school of São Paulo concerning the job/ role of the substitute teacher. More specifically, this paper describes and discusses the substitute teacher activity, having as focuses two activity systems: understanding this professional s job at the school and developing a reading proposal as a support to the substitute teacher s job. To do so, meetings among the voluntary participants were carried out among titular teachers (this researcher among them), temporary teachers (OFAs), and substitute teachers. During the meetings, each participant expressed their point of view about the job/ role of the substitute teacher. The organization of this paper is based on the collaborative critical methodology (MAGALHÃES, 2006), in order to set a locus of critical collaboration aimed at a critical reflection about the actions of the participants on negotiating understandings and proposals which could provide transformation to the substitute teacher s reality in the context of the school. The study of the continuous academic background of this teacher as a collaborative and critical professional in the relationship with their partners is supported in the discussions of Vygotsky, Leontiev, Freire (1996); Engestrom (2009) LIBERALI( 2004 and 2008) and MAGALHÃES, (2004 and 2006), among others. As a result of the initial discussions, a proposal based on reading was begun, based on the Proposta Curricular do Estado de São Paulo (2008) and on the Projeto de Leitura nas Diversas areas do Conhecimento (LACE- fase 1,2002). The focus on reading was decided by the group of participant teachers, since one of the main focuses of the school in which most students have difficulties in reading and writing. The results show that: a) the initial meanings of the participants about the substitute teacher underwent some transformations except for one of the titular teachers who attended this research; b) the relations among people in the group of teachers led to a recognition of the importance of the HTP sessions use to discuss the theories which involve the teacher s practice; c) the discussed proposals have features of traditional teaching; d) the material initially developed isn t complied with the curricular proposal (2008) of São Paulo / Este trabalho tem como objetivo compreender criticamente o processo de construção de significados compartilhados por um grupo de professores de uma escola da Rede Pública Estadual de São Paulo, quanto ao trabalho/papel do professor eventual . Mais especificamente, descreve e discute a atividade do professor eventual, com foco em dois sistemas de atividade: a compreensão do trabalho desse profissional na escola e a produção de uma proposta com leitura como apoio para o trabalho do professor eventual. Para tanto, foram realizados encontros com um grupo de participantes voluntários: professores titulares (entre os quais esta pesquisadora), OFAs e professores eventuais. Nessas ocasiões, cada participante pode expor a sua visão sobre o trabalho/papel do eventual. Esta pesquisa está organizada com base na Metodologia Crítica de Colaboração (MAGALHÃES, 2006), para criação de lócus de colaboração crítica, voltada à reflexão crítica sobre as ações dos participantes na negociação de compreensões e propostas que trouxessem transformação à realidade do professor eventual, no contexto da escola. O estudo sobre a formação contínua desse professor, como profissional colaborativo e crítico na relação com seus pares, está apoiado nas discussões de Vygotsky (1934), Leontiev (1978), de Freire (1970/2005); Engestrom (1999 ), LIBERALI ( 2004 e 2008) e MAGALHÃES (2004 e 2006), entre outros. Como resultado das discussões iniciais, foi principiada a produção de uma proposta de trabalho em leitura, com base nos pressupostos da Proposta Curricular do Estado de São Paulo (2008) e no Projeto de Leitura nas Diversas áreas do Conhecimento (LACE- fase 1,2002). O foco na leitura foi decidido pelo grupo de professores participantes, uma vez que esta é uma questão central da escola, em que a grande maioria dos alunos apresenta dificuldades em ler e escrever. Os resultados apontam que: a) os sentidos iniciais dos participantes sobre o professor eventual sofreram transformações, exceto para um dos professores efetivos participantes; b) as relações, entre o grupo de professores, levaram à constatação da relevância das sessões de HTPC direcionadas para discussão das teorias que envolvam as práticas do professor na escola, em lugar de discussões utilitárias; c) as propostas discutidas apresentam características de um ensino tradicional; d) o material inicial produzido não está voltado para a proposta curricular (2008) do Estado de São Paulo